In 2006, Elliott et al 1 reported that children age 2-6 years in a crash had a lower risk of death when using a child restraint (car seat or seat belt with booster seat), compared with a seat belt only: risk ratio (RR) 0.79, and 0.72 if restraint misuse was excluded. In 2009, Rice et al 2 3 reported that child restraints, compared with seat belts, did little to reduce mortality for children age 2-8 years: RR 0.52 for a child younger than 1 year, 0.51 for age 1, 0.93 for age 2, 1.05 for age 3, 0.89 for 4-5 years, and 1.15 for 6-8 years. In a letter, Elliott et al 4 argued that because Rice et al 2 included adults in their study, their estimates might be biased. In response, Rice and Anderson 5 estimated that for children age 3 years and younger the RR for death in a safety seat, compared with a seat belt, was 0.85 if the analysis included adults and 0.94 if adults were excluded. In their articles in this issue of Injury Prevention, Elliott ( see page 367), 372), 7 expand on this question: will a study of child restraints be biased if adults are included?.
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